1. Field of the Invention
The present invention relates to a method of manufacturing a nozzle plate and a method of manufacturing a liquid ejection head, by which a lyophobic (liquid-repellent) film is formed on a recess-shaped counterbore section.
2. Description of the Related Art
There are methods for forming a lyophobic film on the liquid ejection surface of a nozzle plate formed with nozzles, in which the lyophobic film is not formed on the inner walls of the nozzles. For example, there are a method in which a lyophobic film is formed only on the liquid ejection surface of a nozzle plate after embedding a filling material into the nozzles, and a method in which a lyophobic film is formed over the whole surface of a nozzle plate, and the unwanted portions are then removed.
Japanese Patent Application Publication No. 9-267478 discloses a method where a lyophobic film is formed on the whole surface of a nozzle plate in which nozzles are opened in a flat liquid ejection surface, whereupon an elastic body (silicon rubber or fluorine rubber) in the form of a sheet is attached to the flat liquid ejection surface and the lyophobic film on the inner walls of the nozzles is then removed by using an active gas.
However, in a method which embeds a filling material into the nozzles, there is a problem in that it is difficult to fill the material uniformly into all of the nozzles, in such a manner that none of the filling material projects beyond the opening of any of the plurality of nozzles. If the filling material projects from the opening of a nozzle on the liquid ejection surface, then a lyophobic film will not be formed in the vicinity of the edge of the nozzle opening. Furthermore, if the filling material is not embedded uniformly into all of the nozzles, then the state of formation of the lyophobic film in the vicinity of the nozzle opening on the liquid ejection surface will vary from nozzle to nozzle, and consequently there may be a variation in ejection characteristics between the nozzles. In particular, in a nozzle plate in which recess-shaped counterbore sections are formed, it is very difficult to embed a filling material into the nozzles which open respectively at the bottom surface of the counterbore sections in such a manner that there is no projection of the filling material from any of the nozzle openings and in such a manner that the filling material is embedded uniformly into each of the nozzles.
Moreover, in the method described in Japanese Patent Application Publication No. 9-267478, if recess-shaped counterbore sections are formed in the liquid ejection surface of the nozzle plate, then it is very difficult to attach a sheet-shaped elastic body in such a manner that it adheres tightly to the edges of the nozzle openings which are disposed in the bottom surfaces of the counterbore sections, and hence there is a problem in that the lyophobic film in the vicinity of the edges of the nozzles openings is removed and the ejection performance deteriorates.
Furthermore, since the elastic body is damaged when the lyophobic film is removed, then there is another problem in that the elastic body cannot be reused.